Whilst working on my old Honda I discovered that the Keihin main jets are exactly the same thread and length as the TK mains.
This may be of interest to any experimenters and tuners, I think you will find they are easier to source in more sizes.
The series is Keihin 99-101-393 and then the hole size.
We just need too find a base line number for the Keihins as the numbers do not compare like for like.
I know Mikunis work but thread is not a perfect match.
Could provide hours of fun for any techies.